Integrated circuits include many electronic devices, such as transistors or capacitors, in active areas of a substrate. In a majority of cases, active areas comprise silicon and various integrated circuit components are isolated from one another by an insulating material, such as a silicon oxide. Integrated circuits with feature dimensions less than about 0.25 μm (250 nm) use shallow trench isolation (STI) to isolate the active areas. Various insulating materials, such as silicon dioxide or silicon nitride, have been used for STI.
To form the electronic devices in the active areas, a photolithography act is conducted on the silicon, followed by a dry etch act to remove portions of the silicon and form STI trenches, a strip act to remove, for example, photoresist, a wet etch act to remove contaminants, such as metal contaminants, an STI oxidation to form a liner in the STI trenches, and an STI oxide fill to fill the STI trenches. Various acts in the STI formation process cause oxidation of the silicon and damage to a surface of the silicon. Forming the liner in the STI trenches also consumes silicon because the liner is formed using a thermal growth process. Therefore, many of the process acts consume silicon, decreasing the active area efficiency. Metal contaminants and polymers are also formed during the process, the removal of which may also consume silicon. As the density of integrated circuits continues to increase and the size of electronic devices in the integrated circuits decreases, the loss of any silicon otherwise available to form circuit components in a high density configuration becomes problematic.